title: Left atrial late gadolinium enhancement with water-fat separation: the importance of phase-encoding order.
abstract: OBJECTIVE
  To compare two late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) methods: a Dixon LGE sequence with sequential phase-encoding order, reconstructed using water-fat separation, and standard fat-saturated LGE.
  
  
  METHODS
  We implemented a dual-echo Dixon LGE method for reconstructing water-only images and compared it to fat-saturated LGE in 12 patients prior to their first pulmonary vein isolation (PVI) procedure. Images were analyzed for quality and fat-suppression. Regions of the left atrium were evaluated by a blinded observer (1 = prominent enhancement, 0 = mild or absent enhancement) on two sets of images (fat-saturated and water-only LGE) and agreement was assessed.
  
  
  RESULTS
  Water-only LGE showed a trend toward better fat-suppression (P = 0.06), with a significantly more homogeneous blood pool signal and reduced inflow artifacts (both P < 0.01). Agreement between fat-saturated LGE and water-only methods was found in 84% of regions, significantly correlated by chi-squared test (P < 0.001). The kappa value was 0.52 (moderate). The average number of enhancing segments was higher for fat-saturated LGE than water-only LGE (4.2 ± 2.7 vs. 3.2 ± 2.9, P = 0.03).
  
  
  CONCLUSIONS
  The two-point Dixon LGE technique reduces artifacts due to a centric k-space order. A similar enhancement pattern was observed irrespective of the LGE technique, with more enhancement detected by fat-saturated LGE.
authors.affiliation: Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; Department of Biomedical Sciences, Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.
authors.forename: Jaime L
authors.initials: JL
authors.lastname: Shaw
authors.forename: Benjamin R
authors.initials: BR
authors.lastname: Knowles
authors.forename: James W
authors.initials: JW
authors.lastname: Goldfarb
authors.forename: Warren J
authors.initials: WJ
authors.lastname: Manning
authors.forename: Dana C
authors.initials: DC
authors.lastname: Peters
mesh_terms: D000273:Adipose Tissue / Q000473:pathology*; D000465:Algorithms; D001281:Atrial Fibrillation / Q000150:complications / Q000473:pathology*; D001834:Body Water / Q000166:cytology*; D003287:Contrast Media; D005260:Female; D005682:Gadolinium; D006325:Heart Atria / Q000473:pathology; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D017682:Myocardial Stunning / Q000209:etiology / Q000473:pathology*; D011300:Preoperative Care; D011667:Pulmonary Veins / Q000601:surgery; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D013382:Subtraction Technique
chemical_list: D003287:Contrast Media; D005682:Gadolinium
keywords: Dixon; atrial fibrillation; delayed enhancement; fat-water separation; late gadolinium enhancement; left atrium; pulmonary vein isolation